Image-guided minimally invasive procedures have made a substantial impact in improving patient management, reducing the cost, morbidity and mortality of treatments, and malung therapies available to patients who would otherwise have no option. X-ray fluoroscopy and MRI are two powerful tools for guiding interventional procedures, but they have very different strengths and weaknesses. X-ray fluoroscopy offers very high spatial and temporal resolution and is excellent for guiding and deploying devices. However, it offers little in the way of soft tissue contrast. MR offers tomographic imaging with complete freedom of plane orientation, outstanding soft tissue discrimination, and the ability to portray physiology and directly observe the effect of therapies. However, it not ideal for imaging devices and is limited in spatial resolution. As a result of these disparate characteristics, the choice of guidance modality involves a compromise. Our preliminary work has shown that it is feasible to fully integrate an x-ray fluoroscopy system into the bore of an interventional MR scanner. The two systems can have congruent fields of view, enabling the physician to seamlessly and flexibly choose the modality that is best suited to each phase of the procedure. This type of hybrid system could have enormous impact in the diagnosis and treatment of oncologic, cardiovascular, and other disorders. The proposed work will take the system beyond proof of concept and into the clinic. We will develop and implement more powerful and reliable x-ray subsystems, perfect their MR compatibility, develop x-ray tube designs with increased immunity to magnetic field alignment, and more thoroughly integrate the two modalities by implementing graphic prescription of MR slices from x-ray projections. We believe this technology will have significant benefit to a number of important applications, ranging from endovascular procedures to biopsies and diagnostic studies. However, we are using two applications (TIPS placement and chemoembolization) as models with which to develop this technology, and as part of the proposed work we will conduct small clinical trials of these procedures. The hybrid system, once perfected, will remove the compromise involved in choosing a guidance modality, improving and enabling new minimally invasive procedures.